title: Thermal-work strain during Marine rifle squad operations in Afghanistan.
abstract: The physiological burden created by heat strain and physical exercise, also called thermal-work strain, was quantified for 10 male Marines (age 21.9 ± 2.3 years, height 180.3 ± 5.2 cm, and weight 85.2 ± 10.8 kg) during three dismounted missions in Helmand Province, Afghanistan. Heart rate (HR) and core body temperature (T core) were recorded every 15 seconds (Equivital EQ-01; Hidalgo, Cambridge, United Kingdom) during periods of light, moderate, and heavy work and used to estimate metabolic rate. Meteorological measures, clothing characteristics, anthropometrics, and estimated metabolic rates were used to predict T core for the same missions during March (spring) and July (summer) conditions. Thermal-work strain was quantified from HR and T core values using the Physiological Strain Index (PSI) developed by Moran et al. July PSI and T core values were predicted and not observed due to lack of access to in-theater warfighters at that time. Our methods quantify and compare the predicted and observed thermal-work strain resulting from environment and worn or carried equipment and illustrate that a small increase in ambient temperature and solar load might result in increased thermal-work strain.
authors.affiliation: Biophysics and Biomedical Modeling Division, U.S. Army Research Institute of Environmental Medicine, 44 Kansas Street, Building 42, Natick, MA 01760.
authors.forename: Alexander P
authors.initials: AP
authors.lastname: Welles
authors.forename: Mark J
authors.initials: MJ
authors.lastname: Buller
authors.forename: Lee
authors.initials: L
authors.lastname: Margolis
authors.forename: Demetri
authors.initials: D
authors.lastname: Economos
authors.forename: Reed W
authors.initials: RW
authors.lastname: Hoyt
authors.forename: Mark W
authors.initials: MW
authors.lastname: Richter
mesh_terms: D000328:Adult; D055826:Afghan Campaign 2001-; D000886:Anthropometry; D001831:Body Temperature; D003020:Clothing; D006339:Heart Rate; D018882:Heat Stress Disorders / Q000503:physiopathology*; D006801:Humans; D008889:Military Personnel; D008954:Models, Biological; D009326:Naval Medicine; D005082:Physical Exertion / Q000502:physiology*; D012621:Seasons; D014481:United States; D014887:Weather; D055815:Young Adult